Barrett Technology, Inc. of Newton, Mass., USA has developed an ultracompact, high-performance motor controller (UCHPMC) which provides rotor-position sensing, electronic commutation and motor-current amplifiers with precise current sensing in a cylindrical module measuring only 19 mm (diameter)×8 mm (tall), roughly matching the diameter of the smallest ultracompact, high-performance brushless DC motors. See, for example, U.S. Pat. Nos. 7,511,443; 7,854,631; and 7,893,644.
This small size UCHPMC is especially difficult to achieve with low cost because the need for affordability dictates that only conventional printed circuit board (PCB) techniques be used (i.e., no hidden or blind vias or microvias); and the silicon integrated circuits (ICs) must be conventionally packaged (e.g., no flip-chip techniques with special wire bonding), although moderate layer counts (e.g., 6 layers) are possible.
The UCHPMCs of Barrett Technology, Inc. are especially convenient because the motor controller and the means for sensing the instantaneous motor position are included in the same module, thereby eliminating a large number of electrical conductors and electrical connectors. Furthermore, the small size of the UCHPMCs allows them to be mounted to the back (i.e., body) of a brushless DC motor in the volume of space normally reserved for just the rotor-position sensing feature, hovering just above a tiny magnetic or optical target that spins with the rotor of the motor (it is the detection of the tiny magnetic or optical target which provides the rotor-position sensing feature of the UCHPMC).
The UCHPMCs of Barrett Technology, Inc. provide a significant advance in the field of motor controllers. However, even with the UCHPMCs of Barrett Technology, Inc., there remain several problems with the application of the UCHPMC modules. For one thing, the UCHPMC modules require a rigid and robust mechanical connection between the UCHPMC body and the body of the motor in order to permit effective rotor-position sensing. For another thing, the scheme for (1) making robust electrical connections between the UCHPMC and the motor windings (and any thermistors or redundant Hall position sensors) coming from the motor body, and (2) making robust electrical connections between the UCHPMC and the bussed power and bussed serial communications, require a large amount of hand soldering. The manual nature of these solder connections allows occasional cold solder joints, which can result in inconsistent quality control. Furthermore, where electrical connection failures occur, these failures often occur in the field after the systems have been tested and shipped to the customer. At that point, the electrical connection failures can be difficult and time-consuming to remedy. In addition, where the UCHPMC fails in the field, replacing the UCHPMC requires that the UCHPMC module be disconnected (both mechanically and electrically) from the back (i.e., body) of the motor. This can be inconvenient and time-consuming to effect, particularly when the motor and UCHPMC module are positioned deep within a larger assembly (e.g., within the interior of a robot or robot limb).
Thus there is a need for a new method and apparatus for connecting an ultracompact, high-performance motor controller (UCHPMC) to an ultracompact, high-performance brushless DC motor which provides reliable mechanical and electrical connections between the UCHPMC and the motor, and which allows the UCHPMC to be quickly and easily “swapped out” in the event that the UCHPMC needs to be replaced.
There is also a need for a new method and apparatus for connecting other motor controllers to electrical motors which provide reliable mechanical and electrical connections between the motor controller and the electrical motor, and which allows the motor controller to be quickly and easily “swapped out” in the event that the motor controller needs to be replaced.
There is also a need for a new method and apparatus for interfacing a given motor controller, such as a specific UCHPMC, to a large family of different motors without requiring changes to the UCHPMC component itself.